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120A- WOBC H05 Electrical safety day 1
- 2. UNCLASSIFIED UNCLASSIFIED ACTION: Apply electrical systems safety requirements CONDITIONS: Given a classroom environment, regulatory guidance, and applicable personal protective equipment, STANDARD: Apply regulatory safety requirements to electrical systems in accordance with the NFPA 70E, NEC, NESC, and EM 385- 1-1.
- 3. UNCLASSIFIED UNCLASSIFIED • Safety Requirements: None • Risk Assessment Level: Low • Environmental Considerations: None • Evaluation: Students will be evaluated on this block of instruction during the Electrical Systems and Design Examination 2. Students must receive a score of 70 percent or above to receive a GO.
- 4. UNCLASSIFIED UNCLASSIFIED NFPA 70E National Electric Code (2017) NFPA 70 Standard for Electrical Safety in the Workplace (2015/2018) NESC® National Electrical Safety Code. 2017 EM 385-1-1 OSHA Safety and Health Requirements. (30 Nov 2014) 29 CFR 1910
- 5. UNCLASSIFIED UNCLASSIFIED • LSA 1: Understand Basic Terms and References • LSA 2: Classify electrical hazards. • LSA 3: Understand limits of approach • LSA 4: Arc Flash • LSA 6: Identify rubber line safety equipment and describe the purpose, inspection, testing, and storage requirements (if applicable) for each S3D03-5 Lesson Objectives
- 6. UNCLASSIFIED UNCLASSIFIED • Covered • Not Covered • Mandatory Rules • Permissive Rules • Explanatory Material
- 7. UNCLASSIFIED UNCLASSIFIED • Arc flash hazard • Arc flash suit • Arc rating • Bonded • Bonding jumper • Boundaries • Arc flash • Limited approach • Restricted approach • Current limiting protective device • De-energized • Disconnecting means • Electrical hazard • Electrically safe work condition • Exposed • Hazard
- 8. UNCLASSIFIED UNCLASSIFIED • NESC • Applicability • EM 385-1-1 • applicability
- 9. UNCLASSIFIED UNCLASSIFIED S3D03-9 General Categories 1) Electric Shock 2) Arc-Flash 3) Arc-Blast
- 10. UNCLASSIFIED UNCLASSIFIED Electrical Shock • Occurs upon contact of body part with electrical source • Small currents can be imperceptible • Large currents make it impossible to let go and may cause serious injury or death • 30,000 nonfatal shock accidents occur each year and 1000 fatalities from electrocution with more than half attributed to systems with less than 600V • Fourth leading cause of industrial fatalities, surpassing traffic, homicide, and construction accident deaths
- 11. UNCLASSIFIED UNCLASSIFIED Arc-Flash • Occurs when electric current passes through air • Ungrounded conductor to ungrounded conductor • Ungrounded conductor to grounded conductor • Arc temperatures can reach 35,000ºF • Burns the skin directly • Causes ignition of clothing, adding to burn injuries • Most hospital admissions are due to arc flash, not shock • Over 2000 admissions to burn centers per year • Can kill at distances of 10ft
- 12. UNCLASSIFIED UNCLASSIFIED Arc-Blast • Explosive expansion of air and metal in the arc path • Copper – 1:67,000 times expansion from solid to vapor • Dangers involve: • High pressures – Easily exceed hundreds or thousands of lbs/ft2, rupturing eardrums and collapsing lungs • Sound – Levels can exceed 160 dB • Shrapnel – Surrounding material and molten metal is expelled away at over 700mph, which can completely penetrate the body
- 13. UNCLASSIFIED UNCLASSIFIED • What are the three categories of electrical hazards? • What is electric shock? • What is an arc flash? • What is an arc blast?
- 14. UNCLASSIFIED UNCLASSIFIED • NFPA 70E- Appendix C • Arc Flash Boundary • Limited Approach Boundary • Limited Space • Restricted Approach Boundary • Restricted Space
- 16. UNCLASSIFIED UNCLASSIFIED Safe Approach Distance (limited approach boundary) • Unqualified persons are safe when they maintain a distance from the exposed energized conductors or circuit parts, including • longest conductive object being handled • cannot contact or • enter a specified air insulation distance to the exposed energized electrical conductors or circuit parts. • Must not cross the arc flash boundary unless they are wearing appropriate personal protective clothing and are under close supervision of a qualified person • Only when continuously escorted by a qualified persons should an unqualified person cross the limited approach boundary • Under no circumstance should an unqualified person cross the restricted approach boundary, where special shock protection techniques and equipment are required.
- 17. UNCLASSIFIED UNCLASSIFIED Safe Approach Distance • Determine arc flash boundary • If boundary must be crossed, appropriate arc-rated protective equipment must be utilized • For a person to cross the limited approach boundary and enter the limited space, the must: • Be qualified to perform the task • Be able to identify the hazards and associated risks with the tasks to be performed • To cross the restricted approach boundary and enter the restricted space, qualified persons should meet the following criteria: • Have an energized electrical work permit authorized by management • Use PPE that is rated for the voltage and energy level involved. • Minimize likelihood of bodily contact • Use insulated tools
- 18. UNCLASSIFIED UNCLASSIFIED Basic Equations for Calculating Arc Flash Boundary Distances. NFPA 70E Annex D discuses the methods
- 19. UNCLASSIFIED UNCLASSIFIED Glove Classifications • Labels • Cemented onto cuff • Display size and class • Test dates – Stamped onto cuff, typically near label • Testing is required periodically • Before first issue • Every 6 months thereafter
- 20. UNCLASSIFIED UNCLASSIFIED Sleeves • Worn with gloves to protect arms and shoulders • Same class ratings as gloves • Require the same care as gloves and regular cleaning, inspection, and testing • Also have rubber cemented labels that id size and class • Test dates typically stamped near labels • Testing is required periodically • Before first issue • Every 12 months thereafter
- 21. UNCLASSIFIED UNCLASSIFIED Blankets • Covers odd-shaped conductors or equipment • Some blankets contain a “slot” for increased versatility • Available in different classes of protection • Stored in canvas rolls or metal containers for protection • Held in place with magnets, non-conductive ropes/clamps • Test dates stamped on blanket, can be placed anywhere • Testing is required periodically • Before first issue • Every 12 months thereafter
- 22. UNCLASSIFIED UNCLASSIFIED Line Hoses • Cover distribution conductor • Various lengths, diameters, configurations, and voltage classes available • Require regular cleaning/inspection for cuts/corona damage • Test dates stamped anywhere • Testing is required periodically • Upon indication that insulating value is suspect • Not to exceed intervals of 3yrs
- 23. UNCLASSIFIED UNCLASSIFIED Insulator Hoods • Available in several styles/types • Overlap with line hoses • Available in different voltage classes • Require regular inspection and cleaning • Test dates stamped anywhere • Testing is required periodically • Upon indication that insulating value is suspect • Not to exceed intervals of 3yrs
- 26. UNCLASSIFIED UNCLASSIFIED • Complete Quiz 1 located in Blackboard
- 27. UNCLASSIFIED UNCLASSIFIED • Understand Basic Terms and References • Classify electrical hazards. • Understand limits of approach • Arc Flash • Identify rubber line safety equipment and describe the purpose, inspection, testing, and storage requirements (if applicable) for each